To blanch greens, add greens to a pot of boiling water for 30 seconds
Strain boiling water off and quickly transfer to ready bowl of ice and water
Let cool then strain, dry greens and set aside
In large sauté pan on medium-high heat melt butter and oil together
Add onions and garlic, cook until slightly browned, about 4-6 minutes
Add collard greens and black and red pepper and cook for 5-8 minutes on high-heat, stirring constantly
Remove from heat; add vinegar if desired and stir